Analysis on Genetic Diversity of Radix Astragali by ISSR Markers

Radix Astragali has been an important traditional Chinese herbal medicine for over 2000 years. It is derived from two plant species, namely, Astragalus mongholicus [Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao] and Astragalus membranaceus [Astragalus membranaceus (Fisch.) Bge.] (Leguminosae), according to the Pharmacopoeia of the People’s Republic of China. In this study, the genetic diversity and genetic relationships of Radix Astragali in China were analyzed by Inter-Simple Sequence Repeat (ISSR) markers. A total of 25 highly polymorphic ISSR primers were selected to amplify 95 Radix Astragali samples. Among 273 DNA bands amplified, 213 are polymorphic (percentage of polymorphic bands: 78%). The average value of the amplified bands was 10.9 for each primer, and the number varied from 4 to 20. The genetic diversity of the 95 Radix Astragali samples was analyzed by using POPGENE 1.32 software. The Nei’s genetic diversity index (h) and Shannon’s information index (I) were 0.3590 and 0.5308, respectively, which indicated the abundant genetic diversity of Radix Astragali. The level of genetic diversity in A. membranaceus (h: 0.3109, I: 0.4657) was slightly lower than that in A. mongholicus (h: 0.3364, I: 0.4969). Considering the average genetic similarity coefficient by NTSYS analysis to cluster the A. membranaceus of nine habitats and A. mongholicus of five habitats, Radix Astragali samples were clustered into two groups according to place of origin. This clustering is different from traditional clustering, which divides groups according to species. Results obtained from this study will provide a theoretical basis for the molecular study on germplasm resources of Radix Astragali.